HTTP/1.1 connections stay alive by default, unless the client or server indicates it will close with the Connection: close header. After a timeout, the connection typically closes anyway.
httpd in this case sends back a 408 Request Timeout response. This is unusual. I did not exhaustively study the RFCs, but 408 seems primarily for indicating that the client is sending the request too slowly. If the server has already finished the request, then 408 would not apply. Other servers don't seem to send 408 either. When they have decided that a keepalive connection is too old, they simply close it. In my case, I'm not running httpd server, but the go http client complains about receiving unexpected data.
